Proteins, particularly keratins, are beneficial in healing damaged epithelial tissues. Unfortunately, the chemical and engineering properties of proteins, such as keratins, have been relatively limited to those achieved using oxidative and reductive chemistries, and side chain protein/protein crosslinks. Water is inherently biocompatible. One strategy that has been effectively used to improve the biocompatibility of certain materials has been to infuse the material with a large amount of water. In some cases, synthetic materials that are only moderately tolerated by the human body have been rendered more biocompatible when formulated as low solids hydrogels. Certain proteins, such as keratin, are inherently biocompatible. Hydrogels made from biocompatible proteins have the advantage that they can have a relatively high solids content while retaining a high level of biocompatibility.
Previous keratin hydrogels either were particulate in nature and/or were crosslinked through cystine residues. Disulfide crosslinks are not hydrolyzable. As a result, the hydrogels were not readily biodegradable. In general, the mechanical, chemical, and biological properties of these keratin hydrogels were difficult to control.
Proteinaceous hydrogels, particularly keratin hydrogels, are needed which afford broad control over mechanical, chemical, and biological properties, while maintaining the biocompatibility and healing activity of the proteins.